ZRANGEBYSCORE for score-based queries in Redis - Step-by-Step Execution

Concept Flow - ZRANGEBYSCORE for score-based queries

Start with Sorted Set

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Specify min and max scores

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ZRANGEBYSCORE command runs

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Redis scans sorted set for members with scores in range

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Return members sorted by score

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End with filtered list

The command takes a sorted set and a score range, then returns all members whose scores fall within that range, sorted by score.

Execution Sample

Redis

ZADD myset 1 "one" 2 "two" 3 "three"
ZRANGEBYSCORE myset 1 2

Add three members with scores, then get members with scores between 1 and 2 inclusive.

Execution Table

Step	Command	Action	Score Range	Members Found	Output
1	ZADD myset 1 "one" 2 "two" 3 "three"	Add members to sorted set	-	-	-
2	ZRANGEBYSCORE myset 1 2	Query members with scores between 1 and 2	1 to 2	["one", "two"]	["one", "two"]
3	ZRANGEBYSCORE myset 2 3	Query members with scores between 2 and 3	2 to 3	["two", "three"]	["two", "three"]
4	ZRANGEBYSCORE myset (1 3	Query members with scores >1 and <=3	(1 to 3]	["two", "three"]	["two", "three"]
5	ZRANGEBYSCORE myset 4 5	Query members with scores between 4 and 5	4 to 5	[]	[]

💡 No more members in the score range, query ends.

Variable Tracker

Variable	Start	After Step 1	After Step 2	After Step 3	After Step 4	After Step 5
myset	empty	{"one":1, "two":2, "three":3}	{"one":1, "two":2, "three":3}	{"one":1, "two":2, "three":3}	{"one":1, "two":2, "three":3}	{"one":1, "two":2, "three":3}
Output	none	none	["one", "two"]	["two", "three"]	["two", "three"]	[]

Key Moments - 2 Insights

Why does ZRANGEBYSCORE with (1 3 exclude the member with score 1?

Because (1 means exclusive minimum, so scores strictly greater than 1 are included, excluding score 1 itself. See step 4 in execution_table.

What happens if no members fall in the score range?

The command returns an empty list, as shown in step 5 where no members have scores between 4 and 5.

Visual Quiz - 3 Questions

Look at the execution_table, what is the output of ZRANGEBYSCORE myset 1 2 at step 2?

A ["two", "three"]

B ["one", "two"]

C ["one"]

D []

💡 Hint

Check the Output column in row for step 2 in execution_table.

At which step does the query exclude the member with score 1?

A Step 2

B Step 3

C Step 4

D Step 5

💡 Hint

Look at the Score Range and Output columns in execution_table for step 4.

If you change the min score in step 5 from 4 to 2, what would the output be?

A ["two", "three"]

B ["one", "two", "three"]

C []

D ["three"]

💡 Hint

Compare step 3 and step 5 outputs in execution_table.

Concept Snapshot

ZRANGEBYSCORE key min max
- Returns members with scores between min and max
- Inclusive by default, use ( for exclusive
- Results sorted by score ascending
- Returns empty list if no members match

Full Transcript

The ZRANGEBYSCORE command in Redis retrieves members from a sorted set whose scores fall within a specified range. You add members with scores using ZADD. Then, ZRANGEBYSCORE takes a minimum and maximum score and returns all members with scores in that range, sorted by score. You can specify inclusive or exclusive bounds using parentheses. If no members match, it returns an empty list. This visual trace shows adding members and querying different score ranges step-by-step.